Water-soluble acrylamide polymers are employed in a variety of uses, especially as flocculating aids in mining operations and in sewage and water treatment. They have also been found useful as thickeners in the paper industry, the building trade and in secondary oil recovery from partially exhausted wells. However, finely divided water-soluble acrylamide polymers have encountered difficulties in dispersion in aqueous media and from slippery conditions created in a working environment where dust from the finely divided acrylamide polymer is spread on the working surface and wetted by humidity from the air due to its hygroscopic nature. It is therefore desirable to reduce the dusting propensity of such a material yet obtain a composition that is easily handled, readily dispersible and soluble in water.
Acrylamide polymers have heretofore been treated with a wide variety of agents in an attempt to enhance their water dispersibility in the finely divided state. Glycols, polyalkylene glycols and other polyols as well as some of their carboxylic acid esters are one group of materials which have been utilized in this capacity. USP Pat. Nos. 2,751,368; 3,350,338; and 3,839,500. Additionally, free-flow aids have been added to finely divided powders to render them noncaking and to improve their handling properties. U.S. Pat. Nos. 2,751,368 and 3,812,076. 2,751,368 teaches the addition of primarily silicious free-flow aids to a polyacrylic polymer-polyoxyalkylene ester mixture but the amount of silicious material employed there is many times that which we have found to be effective in our composition. A technical brochure relating to the application of a free-flow agent published by the manufacturer of the agent, W. R. Grace, Davison Chemical Division (Publication PA 77-572) teaches the use of amorphous silica gel in a loading of about 1-2 percent to maintain good dry flow properties for solid particulate materials. We have found, surprisingly, that much lower quantities of such free-flow aids impart good dry-flow properties to our composition without significant dust problems.